“Interest”is a critical bridge between cognitive and effective issues in learning. Student’s interest has great impact on learning performance. Hence, it’s necessary to detect student’s interest and make them more engaged in the learning process for productive learning. Student’s interest can be detected based on the facial expression recognition, e.g., smile recognition. However, various head poses, different illumination, occlusion and low image resolution make smile recognition difficult. In this paper, a conditional random forest base...